A traditional sunshade bending positioning device consists of the upper protruding connector, lower concave connector, the positioning rod, the spring pin and the spring, etc. The biggest disadvantage of the traditional bending device is that the bending angle of the upper protruding connector cannot reach the proper angle for scarf joint due to the load of the sunshade supported by the upper umbrella stem, in particular, due to the load of the sunshade, excessive bending will be caused once the scarf rod is detached from the scarf slot, which will cause difficulty in scarf joint.
The auto bending mechanism for sunshade of the patent number 00249751.4 is created to solve this problem, this structure comprises the upper section of bending and the lower section of bending, said upper section of bending being a cylinder with both sides provided with flat scarf joint parts, a through hole is provided in the scarf joint part and the other end is a round pipe; said lower section of bending being also a cylinder with a groove on the top fitting the scarf joint part of the upper section of bending, and scarf joint ribs symmetric on both sides are formed, one pair of ribs are provided with through holes for fixing pin, scarf joint part of the upper section of bending is engaged in the slot of the lower section of bending and is connected with a pin, this device features that: a groove is provided on the scarf joint part of the upper section of bending, an internal spring is provided in the groove, and a pin pivotally connecting the upper section of bending and the lower section of bending passes through the internal spring, a bending connecting rod is placed in the pivotally connected upper section of bending and lower section of bending with the bottom located at the bottom of the lower section of bending, the connecting rod is provided at the end with 2 pulleys connected by a sliding pin, a groove for the pulleys to slide on is provided in the lower section of bending at the bottom of the slot, a positioning plug is fixed on the top of the connecting rod, the top of said positioning plug is fixed with a return spring for fixing with the upper section of umbrella stem, a pulley is mounted in the upper section above of the spring, one end of the umbrella string is connected with the lower nest, another end is connected with the rotating handle after passing the pulley and passing through the return spring, upper section of bending and lower section of bending in order. It is advantageous in graceful appearance, simple operation, durability and the ability of free positioning within the range of 0˜28°, however, it is disadvantageous in complicated structure, high production cost, lack of a labor-saving mechanism, inflexible rotation etc. and needs to be improved.